Antibodies that react with HTLV-I proteins have been found in the sera of adult T-cell leukemia lymphoma (ATL) patients. These antibodies recognize both the gag core antigens and the envelope proteins of the virus. Viral core proteins were readily purified, sequenced, and extensively used in immunoassays; however, progress with the more important viral envelope proteins was slower. A limiting factor, therefore, in the studies of the immune response to these viruses has been the difficulty in isolating the viral envelope proteins in pure form and in quantity.
The proviral DNA of HTLV-I has been cloned Seiki et al., Proc. Natl. Acad. Sci. USA, 79:6899 (1982) and Manzari et al., Proc. Natl. Acad. Sci. USA, 80:1574 (1983)! and sequenced Seiki et al., Proc. Natl. Acad. Sci. USA, 80: 3618 (1983)!. The HTLV-I envelope is expressed by placing it into the pJLA16 derivative Lautenberger et al., Gene Anal. Techniques, 1:63-66 (1984)! of plasmid pJL6 Lautenberger et al., Gene, 23:75 (1983)!. This plasmid contains the 13 amino-terminal codons of the bacteriophage lambda cII gene placed under the transcriptional control of the well-regulated phage lambda p.sub.L promoter. This plasmid is known and has been successfully used to express sequences from myc, myb, and ras oncogenes Lautenberger et al., Gene, 23:75 (1983) and Lautenberger et al., in Gene Amplification and Analysis, Volume 3, Expression of Cloned Genes in Prokaryotic and Eukaryotic Cells, Papas et al (eds), Elsevier, N.Y./Amsterdam, pp. 147-174 (1983).